Bug overview description.
Adding a post to a set should record no action when added through metatag.

What part(s) of the site page(s) are affected?
/post/index (tag scripting)
/post/show/xxxx
/post/update.json//post/update.xml

What is the expected behavior?
No post history record created.

What actual behavior is given instead?
Post history record created.

Time of incident (if applicable).
N/A

Can you reproduce the bug every time?
Yes

What steps did you take to replicate this bug?

• Go to any post page (https://e621.net/post/random)
• Add post to a set using the tag edit box: i.e. set:xxxx
• Check post's history

Errors or other messages returned (if any).
N/A